1. Technical Field
The embodiments herein generally relates to a method of processing seismic data and particularly to a method of processing a multi-component marine seismic data. The embodiments herein more particularly relates to a method of processing a multi-component marine seismic data in order to estimate the properties of the seafloor and sensor calibration filters in a shallow water environment.
2. Description of the Related Art
The marine surveys can also be conducted using the sensors attached to an Ocean Bottom Cable (OBC) laid out on an ocean bottom rather than in towed streamers. Due to the operational limitations, most of these types of surveys are conducted in the water bodies with depths less than 70 meters. However OBC crews in recent years have acquired 3D surveys in depths up to 2000 meters. One operational advantage is that obstacles (such as platforms) do not limit the acquisition as much as they do for streamer surveys. Most of the OBC surveys use the dual component receivers, combining a pressure sensor (hydrophone) and a vertical particle velocity sensor (vertical geophone). The OBC surveys can also use four components, i.e. a hydrophone component plus the three orthogonal velocity sensors. The Four component OBC surveys have the advantage of being able to also record shear waves, which do not travel through water. Hence the multiple component OBC surveys can lead to improved subsurface imaging.
Some of the world's important oil and gas fields are in the Persian Gulf where the average water depth could be as shallow as 10-15 m. 4C ocean bottom cable (OBC) seismic data collected in a shallow water environment record the strong surface waves due to the shallow water depth and hard sea bottom. Also they represent a considerable noise problem not only for the actual shot but also for the subsequent shots due to the inadequate time delays between the shots, resulting in severe contamination of the reflection signals.
Frequency filtering (or widowed frequency filtering) and fk-filtering are the two main processing techniques used currently for extracting the surface waves from seismic records. These methods are insufficient in the shallow water environment for two reasons. First, these two techniques are designed in the frequency domain based on Fourier Transform and have the same effect on the whole time series. This causes errors in seismic data processing because seismic data, being non-stationary in nature, has varying frequency content in time. Secondly, the surface waves are highly dispersed and scattered in the shallow water environment which brings difficulties of defining a single, appropriate reject zone on the f-k panel.
Therefore, there is a need for a method of processing a multi-component marine seismic data in a shallow water environment. There is also a need for a reliable surface wave analysis tool to hydrocarbon exploration and reservoir management of super-giant carbonate reservoirs in the shallow water environment.
The abovementioned shortcomings, disadvantages and problems are addressed herein and which will be understood by reading and studying the following specification.